The sterile sampling of culture liquor from a fermenter is essential for effecting control over the state of the object under study and determining the conditions of its active life environment. All of the laboratory-type and commercial fermenters are provided with devices for sterile sampling of culture liquor. In spite of a great diversity of fermenter designs, there is little structural difference between the various devices for sterile sampling of culture liquor. The sampling of culture liquor from a fermenter is done manually and involves certain operations that are to be performed simultaneously with each other. The sampling is usually done by two researchers, to which end a plug is removed from a sterile sampler in the flame of an alcohol burner and a clamp is released on the culture liquor drain pipe, or valves are operated. The duration of sampling does not enable one to analyze the status of transient processes of microorganism development, which is of special research importance. This latter consideration gave a start to the search for novel structural solutions of devices for sterile sampling of culture liquor from a fermenter.
There is known in the art a device for sterile sampling from a fermenter (cf., data sheet by New Brunswick Scientific Co., Inc., on Model FM 250), comprising a drain pipe with a valve, positioned on the fermenter and having an outlet connection communicating with a steam delivery pipeline. For sampling culture liquor from the fermenter, one should first sterilize a sample collector plugged with a cotton-wool or some other readily removable stopper. Then, the sample collector is connected with the outlet connection and sterilized with steam, and the sampling valve is opened.
When using the afore-described device, part of the culture liquor from the pipeline is to be drained off, this resulting in undesirable losses of culture liquor, especially when carrying out periodic processes of microorganism growing. In addition, the use of this prior art device requires that the culture liquor in the fermenter should always be under excess pressure which is not always convenient and possible in the course of growing microorganisms, or that a transfer pump be used in the drain line. Steam is discharged via outlet connection to the working premises, which aggravates the working conditions of the personnel.
Well known in the art is a device for sterile sampling from a fermenter using antiseptics such as chloramine, comprising a pipeline with a valve for the passage of culture liquor from the fermenter and a pipeline with a valve for the passage of the antiseptic. After the valves, the pipelines are combined in a single line provided with an outlet connection. Cotton wool-plugged test tubes are used as sterilized sample collectors. For sampling, the culture liquor drain valve is opened and, following partial drain of said liquor, the sample collector plug is removed and the sample collector is placed under the stream of liquor. After the requisite amount of culture liquor has been collected, the sample collector is plugged and the drain valve closed. After that, the valve on the antiseptic pipeline is opened and the antiseptic is partly drained; in so doing, the antiseptic should stay in the outlet connection until the next sampling.
This latter prior art device provides for additional drain from the zone of culture liquor stagnation, which leads eventually to losses of said liquor. Also, upon preliminary partial drain of the culture liquor some antiseptic stays on the walls of the outlet connection, which results in the presence of antiseptic in the sample collector and, consequently, in distortion of the analysis results, especially in the case of enzymes.
There is also known a device for sterile sampling from a fermenter, comprising a sampler positioned on the fermenter in the zone of stirring of culture liquor, and a sterile sample collector (cf., data sheet by New Brunswick Scientific Co., Inc., on BIOFLO Model C 30).
This latter device also comprises a drain pipe with a screw clamp, on which pipe there is secured a chamber with a rubber spray bulb or injector, and a joining unit. The sterilized sample collector is set up and joined to the joining unit under the flame of a burner. Sampling is effected in the following manner. Pressure is applied to the rubber bulb while the screw clamp is released, the air being forced from the sample collector to the fermenter. A release of the rubber bulb results in the restoration of its shape and, simultaneously, in the inflow of culture liquor from the fermenter to the sample collector. After that, the screw clamp is closed and the sample collector with sample is replaced with a sterilized empty sample collector under the flame of a burner.
The use of the last-described prior art device requires that a researcher should perform in the course of sampling a whole series of successive operations, which results in considerable time consumption. As a result, one cannot take a substantial number of samples per unit time, as required for the purposes of studying the dynamics of microorganism growth. The use of open flame in the course of connection and removal of the sample collector prohibits the utilization of the device for operation with explosive gases which provide the environment for the growth of some microorganisms. It is not always desirable to return the air to the fermenter upon pressing the rubber bulb, while in the case of microorganisms growing under conditions of a strict ratio of the supplied gases, such as hydrogen-oxidizable bacteria, it is simply inadmissible. Moreover, said prior art device also suffers from the loss of culture liquor which should always be drained from the stagnation zone of the drain pipe prior to sampling.